You have a lot of those as far as fossilized Pokemon are concerned, though! Aerodactyl for instance, as well as Kabutops, and Armaldo, etc etc. They may not be huge, known predators like what we knew in the past(except for Aerodactyl, he's a big meanie), but rest assured that GF has not forgotten to give the prehistoric times some love. XD They usually always do in one way or another.

But none of those are dinosaurs, the only dinosaur fossils we have had so far are Bastiodon (Diceratops) and Rampardos (Pachycephalosaurus) and you may count Tropius as an Apatosaurus. We have had an Archeoptryx (Arceops) and a Pterosaur (Aerodactyl, which is based on the commonly false representation of a Pterodactyl, which in reality, there is no such this as a Pterodactyl, but there is a Pteranodon) and Pterosaurs are not dinosaurs, but prehistoric flying reptiles. I'm talking true be true dinosaurs, like Tyrannosaurus, Stegosaurus, Velociraptor, Brachiosaurus, Parasaurolophus, and many, many other popularized dinosaurs. A Spinosaurid would be an awesome Pokemon! Heck, it looks like one itself (basically a giant, bipedal crocodile with a sail on its back!)